Initial commit
Add 'only_enabled' option to the payment choice type
Introduce payment and transaction models
Add mapping and configuration for new models
Introduce credit card and payment source model
Make CreditCard convertable to string and add masked number
Save the credit card as a source on payment
Add credit card type
Introduce gateway choice type
owner to no owner
typo it should be mutable
Allow nullifying the payment method
Fix payment model
Merge pull request #2 from cordoval/patch-2

[RFC] typo it should be mutable
Fixing a tiny glitch on English translation.
Initializing French translation.
Dutch translations
Init polish translation
Init polish translation
fixed naming mistakes in Payment Entity spec, added credit card form type, added credit card brands, added services for credit card